North American Fruit Explorers mailing list at ibiblio

[Jim F <bonfire58_2000@yahoo.com>]

     Why do so many people believe the 'old wives tale' that pine needles and oak leaves make the soil acidic?

     Upon the first day of my Horticulture class, for a gee-whiz experiment, I grind up dry pine needles, add distilled water, insert a pH meter, and ask a student to read the meter.  "Oh, it's alkyline," is the usual response.  Not very alkyline, really, with a pH of 7.2 to 7.3.  Next, I take a jar of pine needles and oak leaves that have been fermenting for a month and ask another student to read the meter.  "pH 7.0," is the invariable response.  For the last portion of the experiment, I have a third student read the pH meter for a jar of pine needles and oakleaves that have been composting in my garden for a year.  The pH is still 7.0, no more acidic than other composted vegetative matter.

     Every time I encounter a conifer that I hadn't tested before, I collect its needles for a pH test and I have yet to discover acidity among those I have tested.  Perhaps there is a species of conifer, somewhere, whose needles make soil acidic, and if there is, I just haven't found it yet.

Jim Fruth

Pequot Lakes, MN 

 

 

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